Charge forming means



June 23, 1959 A. D. MCDUFFIE 2,891,529

" CHARGE FORMING MEANS 7 Filed June 12,1957 2 Sheets-Sheet 1 FUEL m/vk IN VEN T OR.

- A. D. MCDUFFIE CHARGE FORMING MEANS June 23, 1959 2 Sheets-Sheet 2 Filed Jun 12, 1957 ATTORNEY United States. Patent 2, 91,529 CHARGE FORMING MEANS Archie D. McDuffie, Berkley, Mich., assignor to General Motors (Iorporation, Detroit, Mich, a corporation of Delaware Application June '12, 1957, Serial No. 665,210

13 Claims. (Cl. 123-119) The present invention relates to charge forming means for an internal combustion engine and, more particularly, to means for regulating the fuel pressure in a fuel injection system.

In the past numerous attempts have been made tosupply a fuel injection system which is adapted to sense the amount of airenten'ng the engine and to meter the fuel in response thereto. In one type of system the air flows through a.-venturi and the fuel flows through one or more metering orifices and pressure responsive means are provided for regulating the fuel flow sothat the vacuum in the venturi and the fuel pressure drop across the orifice aremaintained in, some predetermined proportion. Althoughthis type of systemdoes operate satisfactorily, it has been found that in the ordinary automotive engine, the engine operates over a very wide range and if the pressure responsive means. are adapted to withstand the extreme maximum pressure differentials, they are not adequately, sensi'tivevto the minimumpressure differentials to insure, proper metering of the fuel. duringlight loads. Accordingly, it has been extremely. difiicult to provide a fuel injection system of. this type which would properly meter. the fuel throughout the entire operating range of the engine.

It. is now proposedjto provide a fuelinjection system which is not only capable or metering the fuel during all loadranges, but is also adapted to accurately meter the fuel durjng the idle and off idle range. More particularly, this is accomplishedby one means for metering: the fuel in proportion to the flow during. the load range and separate means for, metering the fuel during idle andoifidle range. This separate means comprises a pressureregulator for controllingthe pressure of the fuel supplied to the normalmeteringrmechanism. This pressur e regulator may be operatiyely interconnected with the throttle valve or other load responsive means so het ur n l sht load perat on, the uelp e w l be determin d by, h t ro e. e t e e y a g the rot e pos tion he, ont l n f c o in e amou of fuelflow. However, when the throttle valve is open more than some predetermined amount, the pressureregulator will'maintainthe fuel pressure at some fixed amount and the metering mechanism will be efiective to retain the fuel 9 nseam p edete m nedrmp ti n. h air flow- I thsdmw g a Eigure 1 isa diagrammatic view. of a fuelinjection y memp nslhe pr en tion Figure 2 is a cross-sectional view of the pressure regulator and metering mechanism employed. in the injection system ofFigure 1..

Referring to the drawings in more detail, the present invention may be adapted to be employed in charge forming means for an internal combustion engine such as disclosed and claimed in copending. application Serial No. 634,915, Charge Forming. Means, Archie D. Mc- Dufiie, filed January, 18, 1957., This charge forming. means includes an induction system and a fuel'injection system.

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The induction system 10 comprises a compound atmos pheric intake 12 which is mounted on an intake mani fold 14. The intake 12 includes a 'venturi passage 16 and an auxiliary passage 18 in parallel thereto. These passages 16, 18 are interconnected with each other and the induction passages in the intake manifold 14. A manually actuated throttle valve 20' controls the amount of air flow through the passages 16, 18 into the engine. The throat 22 of the venturi will develop a vacuum signal indicative of the amount of air flow. An auxiliary valve 24 is provided in the auxiliary passage 18 for controlling the flow therethrough. This valve 24 is interconnected with a diaphragm 26 that is interconnected with a trigger unit 28. This trigger unit 28 may be actuated by any suitable means, such as throttle valve 20, that will retain the auxiliary valve 24 completely closed when the induction flow is less than some predetermined amount and to open it when the air flow is above some predetermined amount to admit manifold vacuum from conduit 29 to chamber 88. The proportion between the air flow and the 'venturi throat vacuum will be dependent upon whether the auxiliary valve 24 is open or closed.

The fuel injection system 30 comprises a fuel tank 32 a fuel pump 34 interconnected with the tank 32, a pres sure regulator 36 interconnected with the output of the fuel pump 34, a metering device 38 having an inlet 40 interconnected with the pressure regulator 36 and distributing means 42 for distributing the metered fuel to the various injector nozzles 44. The metering device 38 comprises a pair of diaphragms 46, 48 that are enclosed in a housing 50 and interconnected with each other by a yoke 52 which is pivotally mounted on a pivot pin 54. The air diaphragm 46 has one side thereof exposed to atmospheric air pressure and the other side exposed to the vacuum in the 'venturi' throat by vacuum line 56. Thus there will be a force on the diaphragm 46 indicative of the mount of air flow.

The fuel diaphragm 48 has one side exposed to the fuelpressure in the high pressure chamber 58 and the other side exposed to the fuel pressure in the low pressure, chamber 66. One arm 62 of the yoke 52 bears against the end of a piston valve 64 in the inlet 40 so as to be effective to control the admission of fuel into the high pressure chamber 58. The metering valve 64'comprises'a tapered piston 661that slides in a tapered passage 68 so as to control the opening into the interior 70 of a threaded plug 72. This plug 72 may be positioned to limit, the extend to which the valve 64 may be closed. The high and low pressure chambers 58, 60 are interconnected with each other hy one or more metering orifices 74, 76 and 78so that the fuel flowing through the metering valve 64 may flow through the orifices 74, 7,6 and 78 and into the outlet 84 for distribution to the nozzles. Thus as the fuel flows from one chamber to the other, there will be a force on the diaphragm 48 indicative of the fuel flow. The primary meteringorifice' '74 has a hydraulic resistance that matches the characteristics of the venturi 16 when all of the air is flowing therethrough. It may be seen that as the air and fuel flow through the venturi 16 and primary orifice 74, respectively, the diaphragms 46, 48 will actuate the valve 64 and meter the fuel so that the forces are balanced, i.e., the airand fuel are in some predetermined proportion; In addition, a secondary metering orifice 76 may be provided in parallel to the primary metering orifice 74 so as to also interconnect the two fuel chambers 58,

60. The flow of fuel through this orifice 76 is controlled by a ,valve 82 interconnected with a diaphragm 84 actuated by the trigger unit 28. Thus when the induction air flowis large enough, the trigger. unit 28 will simulchambers 86, 88 and open the auxiliary valve 24 and the secondary orifice 76, thereby maintaining the same relationship between hydraulic resistances of the orifices and the venturi vacuum. In addition, a power enrichment orifice 78 is also provided in parallel to the primary and secondary orifices 74, 76. The flow of fuel through this orifice 78 is controlled by a valve 96 actuated by a diaphragm 92 responsive to the induction vacuum. Normally this valve 90 is retained closed; however, when the induction vacuum is low, the diaphragm 92 will open the valve and permit the fuel to flow through the power enrichment orifice 78. This will decrease the resistance of the orifices and cause the ratio of air to fuel to decrease. Thus the primary and secondary orifices 74, 76 may be set for maximum economy charge, whereas the enrichment orifice 78 will provide a maximum power charge.

The pressure regulator 36 which is disposed between the outlet of the fuel pump 34 and the inlet 40 to the metering device 38 is effective to regulate the fuel pressure in the system 30 by means of a bypass valve 94. This valve 94 has an area 96 on the end thereof exposed to the fuel pressure so that there will be an upwardly opening force on the valve 94. In addition, there is a spring means for biasing the valve 94 closed in opposition to the fuel force. This spring means includes a leaf spring 98 and a coil spring 108 that are tensioned by means of a lever 102 that is interconnected with the linkage for the throttle valve 20. When the engine is driving a load, the throttle valve 20 will be positioned to compress the coil spring 100 completely so that the tension of the leaf spring 98 will control the fuel pressure. This pressure is set high enough to insure an adequate flow of fuel through the system 30 and to permit the diaphragms 46, 48 and valve 64 to meter the fuel in direct proportion to the air flow.

When the throttle valve 20 is in the idle or off-idle range, the air flow will be very small. As a consequence, the forces on the diaphragms 46, 48 are not sufficiently large to insure an accurate metering of the fuel. Accordingly, during this range the throttle linkage will permit the coil spring 100 to expand and to be effective to control the fuel pressure. This spring 100 is matched to the hydraulic resistances of the substantially closed metering valve 64, metering orifices 74, 76, 78, etc. to produce a fuel flow which is a substantially linear function of the throttle setting.

Thus during idle and off-idle ranges the spring 100 will be adapted to meter the fuel flow as a function of the throttle setting and the system will not be subject to the errors that may occur when the diaphragms etc., are lightly loaded. During this range the air-fuel ratio may be regulated by turning the threaded plug 72 to control the amount the piston valve 64 can close. As soon as the throttle valve is sufliciently open, the coil spring 100 will be completely closed and the spring 98 will regulate the fuel pressure. At this point the flow will be adequate to produce an accurate metering of the fuel by the diaphragms 46, 48.

It is to be understood that, although the invention has been described with specific reference to a particular embodiment thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

What is claimed is:

1. Charge forming means for a multicylinder internal combustion engine, said means comprising an induction system for supplying air to said cylinders, a fuel injection system for injecting fuel under pressure into said induction system and having a fuel metering valve effective to meter the fuel in proportion to said air flow, means for limiting the closing movement of said metering valve so that at least some fuel may always flow therepast, a pressure regulator for controlling the pressure of the fuel supplied to said metering valve, said regulator being effective to supply fuel at some predetermined pressure when said metering valve is in the nearly closed position and at another pressure when said valve is in an intermediate position.

2. Charge forming means for a multicylinder internal combustion engine, said charge forming means comprising an induction system for supplying air to said engine cylinders, a fuel pump for supplying fuel under pressure, a fuel metering valve effective to meter the fuel in proportion to the quantity of air flowing through the induction system, means for limiting the closing movement of said metering valve so that at least some fuel may always flow therethrough, a pressure regulator for controlling the pressure of the fuel delivered from said pump to said metering valve, said pressure regulator including first means for regulating the fuel pressure when said valve is in said substantially closed position and second means for regulating the pressure when said metering valve is in the remaining positions.

3. Charge forming means for an internal combustion engine, comprising an induction system for supplying air to the cylinders thereof, a throttle valve for regulating the amount of air flow through said induction system, a fuel pump for supplying fuel under pressure, a fuel metering valve effective to meter the fuel flow in proportion to the quantity of air flowing through the induction system, means for limiting the closing movement of said metering valve so that at least some fuel may always flow therethrough, a pressure regulator for supplying fuel from said pump to said metering valve and effective to control the pressure thereof, said regulator including first means actuated by said throttle valve so as to regulate the fuel flow in response to the position of said throttle valve during a limited range of movement thereof and second means for maintaining the pressure of said fuel at some predetermined amount when said throttle is in the remaining range of positions.

4. A fuel injection system for an internal combustion engine having an induction system with a venturi inlet therein adapted to produce a vacuum pressure signal indicative of the mass of air flow therethrough, said fuel injection systems comprising calibrated metering orifices having the metered fuel flowing therethrough to produce a pressure differential indicative of said fuel, a fuel control valve movable between a partially closed posi tion and a fully open position, pressure responsive means sensitive to said air and fuel pressures for regulating said valve to maintain said pressures in some predetermined proportions, a pressure regulator adapted to control the pressure of the fuel supplied to said valve, said regulator being effective during one range of operation and to prevent the fuel pressure exceeding some predetermined amount, and during another range to prevent said pressure exceeding another amount.

5. A fuel injection system for an internal combustion engine having an induction system with a venturi inlet therein adapted to produce a vacuum pressure signal indicative of the mass of air flow therethrough, said fuel injection system comprising calibrated metering orifices having the metered fuel flowing therethrough to produce a pressure differential indicative of said fuel flow, a fuel control valve movable between a partially closed position and a fully opened position, pressure responsive means sensitive to said air and fuel pressures for regulating said valve to maintain said pressures in some predetermined proportion, a pressure regulator adapted to maintain the pressure of said fuel delivered to said valve at some predetermined amount when said valve is between its extreme positions and to provide a lesser pressure when said valve is in said partially closed position.

.6. The combination of claim 5 wherein said pressure regulator has a low tension spring adapted to control the pressure of said fuel when said control valve is in said partially closed position and a second spring of greater tension adapted to maintain the pressure at some predetermined amount when said control valve is in its remaining positions.

7. A fuel injection system for an internal combustion engine having an induction system with an inlet having a throttle valve for regulating the air flow and a venturi to produce a vacuum pressure signal indicative of the mass of air flowing therethrough, said fuel injection system comprising calibrated metering orifices having the metered fuel flowing therethrough to produce a pressure difierential indicative of said fuel flow, a fuel control valve movable between a partially closed position and a fully opened position, pressure responsive means sensitive to said air and fuel pressures for regulating said valve to maintain said pressures in some predetermined proportions, a pressure regulator operatively interconnected with said throttle valve so as to control the pressure of the fuel supplied to said control valve in proportion to the position of said throttle valve when said throttle valve is in the substantially closed position, said pressure regulator also being effective to maintain the fuel pressure at some other predetermined amount when said throttle valve is in the remaining positions.

8. The combination of claim 7 wherein said pressure regulator includes a first spring which is effective to regulate said pressure in proportion to the position of said throttle valve when said throttle valve is in said substantially closed position and a second spring which is adapted to regulate the fuel pressure when said throttle valve is in the remaining positions.

9. A fuel pressure regulator comprising an inlet adapted to be interconnected with the outlet of a fluid pump, an outlet adapted to be interconnected with a fluid distribution system, a bypass for return to the pump inlet, a by pass valve in said bypass responsive to the pressure in said outlet, a first means for biasing said valve towards the closed position in opposition to said pressure with one force and second means for biasing said valve towards the closed position in opposition to said pressure with another force differing {from that of the first means.

10. A fluid pressure regulator for a fluid flow control system comprising an inlet adapted to be interconnected with a fluid pump outlet, an outlet adapted to discharge said fluid therefrom, a bypass for returning surplus fluid to the inlet of said pump, a bypass valve in said bypass responsive to the pressure in said outlet, a first means for biasing said valve towards the closed position in opposition to said pressure with one force and second means for biasing said valve towards the closed position in opposition to said pressure with another force differing from that or" the first means and means responsive to the operating conditions in said fluid system for regulating the efiectiveness of said first means.

11. A pressure regulator for a fuel system comprising an inlet adapted to be interconnected with a fuel pump, an outlet adapted to be interconnected with a fuel distribution system, a bypass for returning surplus fuel to the pump inlet, a bypass valve in said bypass responsive to the fuel pressure in said outlet, a first means for biasing said valve towards the closed position in opposition to said fuel pressure with one force and second means for biasing said valve towards the closed position in opposition to said fuel pressure with another force differing from that of the first means and means responsive to the load on said engine for regulating the effectiveness of said first and second means.

12. A pressure regulator for a fuel injection system adapted to inject metered fuel into the charge for an internal combustion engine, said regulator comprising a housing having an inlet adapted to be interconnected with a fuel pump, an outlet adapted to be interconnected with said injection system for delivering pressurized fuel thereto and a bypass for returning surplus fuel from said housing to the pump inlet, a bypass valve in said bypass responsive to the fuel pressure in said outlet, a first spring for biasing said bypass valve towards the closed position in opposition to said pressure, a second spring for biasing said bypass valve towards the closed position with a tension greater than the tension of said first spring and means responsive to the operating condition of said engine for causing one or the other of said springs to regulate the pressure in said engine during certain operating conditions.

13. The combination of claim 12 wherein said load on said engine is controlled by a throttle valve which is also adapted to control the tension of said first spring.

No references cited. 

